More than 400 species of moss are found in West Virginia. Some can be identified by eye or with a hand lens, but most must be examined with a microscope. Mosses occur abundantly on exposed and compact soil, decaying organic matter, rotting logs, old burns, rocks, and on the bark of trees. Mosses are bryophytes, which also include liverworts and hornworts. Since mosses are larger and more conspicuous, more is known about these plants.

In West Virginia, sphagnum mosses are among the best-known mosses. These occur in boggy areas. They are used as soil additives and to pack roots of plants, since sphagnums have large hollow cells which retain water, thus staying moist for long periods. Sphagnums are the source of peat reserves.

Haircap moss occurs on a wide range of sites from swampy areas to dry fields. These erect mosses form a dark green, rug-like cover. The tall wiry stems with their spore-bearing capsules are present throughout the year. Another common moss in West Virginia is cushion moss. The light green clumps form cushions and are common on the forest floor of open woodlands.

Carpet moss forms dense mats over fallen logs and rocks. The individual plants resemble coarse ferns. The moss plants form intertwined layers that can be lifted up in large mats without disturbing individual plants. A similar moss is fern moss, which forms carpets over rocks and decaying wood. The plants of fern moss are fern-shaped but have a much more delicate form. Carpet mosses and other "sheet mosses" are harvested in the wild and sold for use in the florist and nursery industries.

Mosses are often the first plants to invade denuded areas, thus stabilizing soil and restricting erosion. Moss carpets facilitate invasion of other plants, preparing the way to a cover of woody plants. Some plants, such as rhododendrons, always seed-in on a moss cover, where moisture conditions are ideal for seeds to germinate.

Mosses absorb large amounts of water and restrict surface runoff, thus reducing erosion. Studies of stem flow on trees show that after light rains, little moisture reaches the forest floor since the dense moss layer near the tree base absorbs most of this water. Moss plants are very sensitive to water and atmospheric pollution and can be used as an early indicator of pollution or environmental stress. No moss species are restricted exclusively to West Virginia, although certain rare species have been found here.